Barruel argued that the secret societies were founded by the Illuminati, a Bavarian Enlightenment society founded in 1776. He claimed that the Illuminati were atheists who were bent on destroying Christianity and the traditional social order. He also claimed that the Illuminati had infiltrated the Freemasons, a fraternal organisation that was already widely distrusted in France.
Barruel's book was a bestseller in France and was translated into several languages. It was widely read by conservatives and reactionaries who were opposed to the French Revolution. The book helped to shape the way that many people understood the Revolution, and it is still cited by conspiracy theorists today.